Prodigies of propagation: the many modes of clonal replication in boloceroidid sea anemones (Cnidaria, Anthozoa, Actiniaria)

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Abstract
Diverse modes of clonal propagation were documented in tiny zooxanthellate sea anemones from the tropical Pacific. All were boloceroidids, as indicated by the tentacles' basal sphincter and the animals' swimming behavior. In one species, single tentacles were pinched off at the sphincter, shed into the coelenteron, and brooded there while regenerating into minute new polyps in ~4 days. Within a day of release, the propagules fed on live prey and swam by lashing the tentacles. A similar process occurs in another species studied, Bunodeopsis medusoides. In a third species a previously undescribed mode of replication was seen. These anemones bore a primary cycle of tentacles that engaged actively in feeding and swimming, were not shed, and showed no sign of producing polyps. Alternating with these tentacles were fan-like clusters of shorter tentacles that were relatively inactive in feeding and swimming. Despite the sphincter at the base of each of these clustered tentacles, they were never shed singly; instead, each cluster separated as a unit that then regenerated into a new polyp. Two other replicative modes were observed in similar, minute boloceroidid anemones collected together in the same habitat: longitudinal fission, not previously reported in boloceroidids, and pedal scission. Modes of replication in these actinians are more diverse than once thought, but the selective forces behind this variation are so far unexplored. These prolific anemones may regularly be taking advantage of their combination of swimming and regenerative abilities to achieve dispersal, not only by sexually produced larvae, but also by cloned polyps.